1. Technical Field
The present invention relates to a centrifugal fan, and a projector including this centrifugal fan.
2. Related Art
A projector or other apparatus known in the art introduces air from the outside and supplies the air to components and the like generating heat within the external casing of the apparatus, by using a cooling mechanism including a cooling fan so as to prevent temperature increase of these components. The apparatus also sucks the air within the external casing and discharges the air to the outside to prevent temperature increase in the interior of the external casing. The cooling fan is constituted by an axial fan which introduces air in the direction of its rotation axis and discharges the air in the direction of the same rotation axis, or a centrifugal fan which introduces air in the direction of its rotation axis and discharges the air in the direction of the centrifugal force produced by the rotation of the fan, for example.
In JP-A-6-108998, there is disclosed a cooling fan (centrifugal fan) which has a thick portion along the opening circumferential edge of an air inlet port formed in a fan case. According to this structure, at least the opening surface of the thick portion has a tapered shape or a convexly curved shape which is narrowed toward the interior of the fan case. This structure can prevent decrease in the intake amount of gas, and can reduce resonant oscillation generated in the fan case.
However, when the projector including the centrifugal fan falls, the impact force generated by the fall reaches the centrifugal fan, and possibly allows an impeller of the centrifugal fan to partially protrude to the outside through an opening corresponding to the air inlet port formed in a housing for supporting the impeller. In this case, the protruding portion of the impeller may catch on the edge of the opening when returning to the original position, resulting in such a condition that returning of the impeller to the original position is difficult. This engagement between the impeller and the edge causes malfunction of the centrifugal fan.
Accordingly, development of a centrifugal fan capable of preventing malfunction caused by drop impact, and a projector including this centrifugal fan has been demanded.